Afonso de Albuquerque (or archaically spelt as Aphonso d'Albuquerque and also spelt as Alfonso, and Alphonso; Portuguese pronunciation: [ɐˈfõsu dɨ aɫbuˈkɛɾk]; 1453 – December 16, 1515), 1st Duke of Goa, was a Portuguese fidalgo, or nobleman, an admiral whose military and administrative activities as second governor of Portuguese India conquered and established the Portuguese colonial empire in the Indian Ocean.

After finishing his education, Albuquerque first served in North Africa and in the Mediterranean where he took part in numerous successful campaigns against the Arabs and the Ottomans. His long military career in these fronts meant he had acquired the military experience needed to operate in the newly reached and vastly unexplored Indian Ocean.

He is generally considered a world conquest military genius, given his successful strategy: he attempted to close all the Indian Ocean naval passages to the Atlantic, Red Sea, Persian Gulf, and to the Pacific, transforming it into a Portuguese mare clausum established over the Ottoman power and their Muslim and Hindu allies.

He was responsible for building numerous fortresses to defend key strategic positions and establishing a net of diplomatic relations. Albuquerque was appointed "Governor and Captain-General of India" and shortly before his death "Duke of Goa", the first Portuguese nobility title landed overseas, by king Manuel I of Portugal, becoming the first Portuguese duke not from the royal family. He was one of the first to commission secure trading relations with China during the Ming Dynasty, also either establishing or improving commercial trades with Siam, Ethiopia, and Persia.

Albuquerque was known as a prodigious maritime commander, who would often engage with and defeat much larger armies and fleets. For example his capture of Ormuz in 1507 against the Persians was accomplished with an army fifty times smaller. Other famous battles and offensives lead by Albuquerque include the conquest of Goa in 1510 and the capture of Malacca in 1511.

Centuries after Alexander the Great, he was the first European whose dream of establishing an empire in India, or in Asia for any matter, controlled from abroad, was successfully accomplished. His military and diplomatic contributions are generally regarded as one of the most vital to help the Portuguese create a colonial empire in Asia as well as reaching the spice routes in the South East Asia and the South West Pacific. He became known as The Terrible, The Great, The Caesar of the East, Lion of the Seas, and as The Portuguese Mars.